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    <span style="font-size: 16pt; color: gray; font-family: Verdana"><strong>Sound hardware</strong></span><hr />
    <strong style="font-size: x-small">
        <br />
    </strong><span style="font-size: x-small">
    This section explains the sound hardware in NES/Famicom and some of the 
    expansion chips found in some carts.<br />
    </span>
    <strong>
        <span class="style2">
    <br />
        </span>
        <span class="style4">
        Internal 2A03/2A07 channels</span><span class="style1"><br />
        </span>
    </strong>
    <strong style="font-size: x-small">
        <br />
    </strong>
    <span style="font-size: x-small">
        The sound processor has five channels,</span> two square waves,
    one triangle wave, one noise generator and one digital sample (DPCM) channel.<br />
    <br />
    <strong>Square 1 &amp; 2<br />
    <br />
    </strong>Produces pulse waves with four duty settings (12.5%, 25%,
    50% and 25% inverted).
    These channels have a hardware sweep unit that can be accessed by the H and I effects.<br />
    Note: There is a bug that resets the duty phase when switching between 
    certain frequencies, this can be heard as a pop and might be noticable when 
    using vibrato or pitch slides across those frequencies.<br />
    <br />
    <strong>Triangle<br />
    <br />
    </strong>Triangle shaped waveform. There is no volume control for this channel, 
    however, due to how the hardware is implemented, the output level of the DPCM 
    channel will affect the volume output of the triangle wave.<br />
    <br />
    <strong>Noise<br />
    <br />
    </strong>Noise generator. Can produce 32k-bit and 93-bit sequences, selectable
    from the instruments duty/noise setting.<br />
    <br />
    <strong>DPCM (Delta PCM)<br />
    <br />
    </strong>Used to play delta modulated samples. Most of the effects (like arpeggio &amp; pitch slides) does 
    not operate on this channel.<br />
    <br />
    <br />
    <span class="style3">Expansion sound</span><br />
    <br />
    The Famicom has the ability to mix sound from expansion chips found in some 
    carts, famitracker now supports a few of those chips. Expansion sound is enabled from the module properties window.<br />
    <br />
    <span class="style1">
    <strong>Konami VRC6<br />
    </strong></span>
    <strong style="font-size: 9pt">
        <br />
    </strong>The VRC6 chip has two square wave channels and one sawtooth wave 
    channel. This chip was used in games like Akumajou Densetsu and Madara by 
    Konami.<br />
    <br />
    <strong>Square 1 &amp; 2<br />
    </strong>
    <br />
    Produces pulse waves like the internal channels, but have eight different duty 
    settings and lacks hardware sweep. <br />
    <br />
    <strong>Sawtooth<br />
        <br />
    </strong>Sawtooth wave generator. This channel has no duty function but 
    still uses that instrument setting to calculate the volume. A volume level too 
    high will cause the wave to wrap around and sounds distorted (happens when duty 
    = 1 and volume = 6).<br />
    <p class="style5">
        Konami VRC7</p>
<p>
        The VRC7 chip contains a stripped down OPLL unit and has 6 channels for FM 
        sound. This chip was used by Lagrange Point.</p>
<p class="style5">
        Nintendo FDS</p>
<p>
        This is a single channel chip used in the Famicom Disk System hardware by 
        Nintendo. The channel uses a 64-step customizable waveform and has a simple 
        frequency modulator.</p>
<p class="style5">
        Nintendo MMC5">
        Nintendo MM        The MMC5 chip has two square wave channels that are identical to the internal 
        2A03 channels except for no hardware sweep function. It was used in the game 
        Just Breed by Enix.</p>


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